Nitrogen Fixation Responses in Sphagnum Mosses to N-Additions to an Alberta Poor Fen, 2012-2015

• Main Authors: R Kelman Wieder, Dale H Vitt, Melanie A Vile, Jeremy A Graham, Jeremy A Hartsock, Jacqueline M.A. Popma, Hope Fillingim, Melissa House, James C Quinn, Kimberli D Scott, Meaghan Petix, Kelly J McMillen
• Format: Dataset
• Language: unknown
• Published: Environmental Data Initiative 2020
• Subjects: Villanova Peatland Biogeochemistry Group; MLPF; ARA; Acetylene Reduction Assay; fens; peatland; nitrogen fixation; nitrogen deposition; Sphagnum Sphagnum angustifolium; Sphagnum Sphagnum magellanicum; Sphagnum angustifolium; Sphagnum magellanicum; Canada; Fort McMurray; Mariana Lake
• Online Access: https://pasta.lternet.edu/package/metadata/eml/edi/471/1

Development of the oil sands has led to increasing atmospheric N deposition, with values as high as 17 kg N ha-1 yr-1; regional background levels <2 kg N ha-1 yr-1. To examine responses to N deposition, over five years, we experimentally applied N (as NH4NO3) to a poor fen near Mariana Lake, Alberta, at rates of 0, 5, 10, 15, 20, and 25 kg N ha-1 yr-1, plus controls (no water or N addition). Between June and August of each year, we measured N2-fixation using the acetylene reduction technique between 2012 and 2015Averaged across all measurement dates, whether described by a linear or segmented regression, N2-fixation rates decreased with increasing N addition. N2-fixation rates were not different between the water addition only treatments and the control treatments (p = 0.44). While increasing N deposition may not substantively change total inputs of new N to bogs, the form of new N inputs shifts to inorganic N in deposition, rather than organic N produced by the microorganisms that are fixing N2.